The other issues do show up again every now and then on the ELF website, when they do another printing. Christopher et al probably won't reprint an older one until they have cleared out the bulk of the #17 issues (a must-have, everyone get their hands on it. Stuffed full of primary Tolkien material publicly available for the first time.)

There is a copy of #8 on ABEbooks and a few other sites, for $12 right now. Other issues do show up occasionally there or on eBay (a bunch just ended, I am guessing it was those that caught your attention.)

I don't think I currently have additional copies of any issues, but I will check. Since there is no "wholesale discount", I tend not to try to keep spares on hand, as the more recent issues are (occasionally) available as back issues, and I'd have to ask more than list price.

The page is being run by Adam Christensen, who while not one of the main editors has always been involved in the publication (his art graces most of the issues, for example). Here is an early post of his, explaining:

New Parma Eldalamberon page ... The new page is up. One of the reasons I've created this page is that, although Chris has a facebook page, he's not really *on* facebook much and it's not really his favorite communication medium. I'm on facebook all the time and really enjoy all of its features so maintaining a Parma page is very easy for me and I can keep it current.